A cobpobation of new jebsey



M. SHOELD.

PGLYPHASE ELECTRIC FURNACE.

APPLICATION mw ov.2o.191a.

1,317,328. Pandsep 3o, 1919.

2 SHEETS-SHEET l.

M. SHUELD.

POLYPHASE ELECTRIC FUIHMCE.A

APPLICATION HLED NOV. 20,19IB.

1,317,328. Patented sepno, 1919.

2 SHEETS-SHEET 2 cago, 1n the county ofCook and UNITED STATES PATENToEEIcE. I

Hm BHOELD, 02EI CHICAGO, ILLINOIS, ASSIGNOB T0 AMOUR FEBTILIZEB WORKS,0F CHICAGO, ILLINOIS, A CORPORATION 0F NEW romrrnasn ELECTRIC Imaan.

Specification of Letters Patent. `Patented Sept. 30, 1919.

Application med November 20, 1918. Serial No. 968,480.

To all whom it may concern:

Be it known that I, Manx Snom, a. subject of the King of Sweden, residinat Chly am of Ilhnois, have invented certain new and useful Improvementsin.'Polyphase Electric Furnaces, of which the following is aspeelication.

The prime object of the present invention is to provide an electricheating furnace for chemical reactions ca able of advantageously usii rpolyphase a ternating electric currents with their welldmown economicaladvanta in such way as to secure the proper istribution of current flowto effect substantiall uniform and even heating of the material7 to betreated, which is usually conveniently supplied -in the form ofbriquets. To this end the electrodes of the circuit are so arranged orgrou and spaced a art and so associated wit or embedded in the materialto be chemically treated that the resulting heating is practicallyuniform throughout the mass. In some 'forms of the invention, as in thecase of three-phase circuits, the electrodes are so inserted or embeddedin the body of material as to constitute a probable combination of deltaor mesh arrangement with the wellknown star connection. In otherinstances, different connections are suitable and elfective. It isdesirable, however,` in order to avoid excessive unbalancing of thesystem, and for other reasons, to prevent the briquets of material fromindividually fusing` or becoming welded together under the great heatattained, and to this end practically infusble, resistance, heatelements desirably of greater specific conductivity than the briquetsthemselves are mixed or Ainterspersed with the latter, whereby bycontacting more or less with one another the form current aths inparallel relation whlch shunt or ivert the currents sutliciently 'tothemselves ,and away from the briquets so that the resistors b reason ofthe currents flowing through t em become highly heated and transmittheir heat by conduction to the "neighboring briquets, the latterbecoming thus hot enou h to effect the-desired chemical reactions, utnot hot enough to fuse. Obviously, i'f the briquets alone were used andany one or more melted or became fused together, the electricalresistance at this point would be greatly reduced, the currentcorrespondingly increased, and the desired balance of the e ectricalsystem disarranged and upset with obvious ob-- cation, an to whichreference sho d be had in connection with the followin detaileddescription, I have shown sever convenient concrete examples of theinvention employed in advantageous manner, each illustrating` ahorizontal cross-section through t e corresponding furnace structure,the refractory or heat-resisting elements and other parts being omitted.

In this drawing,

Figure 1 is a horizontal cross-section 'showing one style of three-phaseelectrode arrangement; l

Fig. 2 illustrates in similar manner a modified three-phaseconstruction;

Fig. 3 shows a two-phase arrangement with a common return; and

Fig. ,4 also indicates a two-phase system of modified type.

Since'the two and three-phase systems are the most common polyphasesystems in use and hence most readily available, the forms o'f furnacedevices incorporating this invention have been illustrated as of thosestyles or character, but it is to be understood that the invention isnot necessarily limited to these particular types of furnaces orelectric systems.

Referrin first to the structure shown in Fig. 1 it w1 l be noted thatthe furnace comprlses an outer hollow aphite or similar electrode 10 ofgeneral e ongated or elli tical form in cross-section incasi or inc osina pair of spaced, graphite e ectrodes 11 an 12, the three beingconnected to the like number of terminals of a three-phase circuit ofsuitable voltage. The comparatively-uniform mixture of lbriquets 13 andresisterelements 14 is continuously slowly fed down through the spacesaround and between these electrodes in a steady stream, the resistance`members collectively or 'ointly forming a number o'f paths in paral elfor the current to pass from electrode to electrode. The specificresistance of the resister-elements or that occasioned by theircomparatively poor electrical contact with one another generates orcauses sufficient heat to raise the teniperature of the adjoining briuets to bring about the desired chemical e ect, it bein understood thatin many instances gas o one kind or another is caused to traverse themixture durin such heating. As an illustration, the briquets, somewhatfusible under high temperature, may be composed of comminuted carbon,alumina, and a suitable binder and the resistance elements may be ofcarbon in one form or another which is comparatively non-fusible, andthe gas may be nitrogen or one rich in nitrogen. It should be observedthat these resistancemembers act collectively or unitedly in groups orsets as heat-producing elements, and also as mechanical separators orspacers for *the briquets. Desrably the electrodes 11 and 12 areseparated such a distance from one another with respect to theirdistances from the larger outer electrode as to producc a substantiallor practically uniform or even heating o the mixture occasioned bysimilar current distribution. This ar- 'rangement of electrodesapproximates a delta connection between the three-phase terminals withprobably some of the currents flowing in star connection distribution.

In Fig. 2 a somewhat different disposition of electrodes is shown. Inthis case three electrodes 20,21 and 22 are placed in equilateraltriangular arrangement, or, in other words, spaced equally apart', andconnected to the terminals of a three-phase circuit. Around these andspaced therefrom is an outer, rounded, neutral c" common return electroe 23 of gieneral triangular form so as to be practically equally distantfrom all of the three electrodes within it. As in the previous instancethe mechanical mixture of briquets and resister bodies passes slowlydown between and around these various electrodes, filling the spaces asshown. Viewed from one standpoint .electrode 23 is the common neutral orjoint return electrode for the system, the currents owing between thethree inner electrodes and it in a manner well understood. The groundingof the neutral is of advantage if the system becomes somewhatelectrically unbalanced thus completing the common return. Viewedsomewhat differently, since the currents can liow directly from oneinner electrode to another and from one inner electrode to the outer oneand back toV another inner one, the system may be considered as a deltaconnection.` As a matter of fact, the arrangement is probably acoinbination o f b oth.sty1es of connection with the resultingadvantages of the practically uniform distribution of currents and heatthroughout the body of briquets. The inner electrodes are spaced fromone another and from the outer electrode, such distances as to result inthis substantially even heating effect. Obviously, the ground connectionmay be omitted if desired.

y In the system of Fig. 3 the two inner electrodes 30 and 31 areconnected to two terminals 32 and 33 of a two phase circuit, the outerring electrode '34 being in electrical connection with a common returnwire 35, the spacing of the electrodes apart being such that the mass ormixture of briquets and resistance-elements is practically evenlyheated.

Another two-phase circuit arrangement is presented in Fig. 4 wherein thefurnace lias an outer-electrode 40 connected to the common returnconductor 41 and containing two chambers or compartments eachaccommodating one of the two electrodes 42 and 43 connected to thetwohase terminals 44 and 45. Each of these eat compartments containsitsown body of mixture all parts of which are heated in like degree. Thecurrents in this instance [low directly between each electrode and thecommon outer electrode.

In these drawings no attempt has been made to show accurately the exactsizes and shapes of electrodes nor the precise disposition or spacingapart of the same, it being the purpose merely to set forth the generalprinciples of the invention in such a way as to enable any one skilledin the art to practice the invention and reap the benefits of itsemployment. It will be clear, therefore, that the invention is notlimited to the precise and exact structural features shown and thatthese ma be modified within comparatively wide imite without departurefrom the essence and substance ofthe invention and without the sacrificeof any of its substantial benefits and advantages. Accordingly it is theaim of theap pended claims to cover all modifications which are withinthe spirit and scope of the invention. l

I claim:

1. A polyphase alternating-current electric heating furnacefor chemicalreactions, comprising a plurality of spaced electrodes adapted to beconnected to the terminals of a polyphase electric circuit and to be incon# tact with the body of material to be heated,

one of said electrodes comprisin a surrounding tubular body throu h wich the material is adapted t'o ass, t e disposition and spacing apartof said electrodes producing substantially-uniform heatin material,substantially as descri v 2. The combination cfa poly-phasealterhating-current electric heating furnace for chemical reactions anda body of material to be heated thereby comprising a mechanical mixtureof briquets to be chemically modied and comparatively-infusibleresisterof thev ylili elements, said furnace comprising a plurality ofspaced electrodes connected to the terminals of a polypliase electriccircuit and in contact with Isaid body of material to be heated throughwhich the currents pass, one of said electrodes comprising a,surroundingr tubular body through which such mixture is adapted to pass,the disposition and spacing apart of said electrodes producingsubstantially-uniforiu heating of the briquets, substantially asdescribed. l

3. A l'iolyphase alternating-current electric heatingr furnace forchemical reactions, comprisinga plurality of spaced electrodes adaptedto be connected to the terminals of a polyphasc electric circuit, one ofsaid electrodescolnprising a surrounding tubular boday through which thematerialV to be heated? i's adapted to pass, the remaining,1relectrodles being adapted to be embedded in such material, thedisposition and spacing;r apart'oi'saiid electrodes producingsubstantiailily-imiffoa'm heating of such material, substaiatiatly asdescribed..

L The combination of a iolyphase altcic -natmgcurrent electric heatingfurnace for elmaieal reactions and a body of material to be heatedthereby comprising,r a mechanical mixture of briquets to 'be'cheuncall'v l)nodilied and comparatively-infusible resister-elemenis,said furnace comprising a' plurality of spaced electrodes connected tothe terminals of a polyphase electric circuit. one of said electrodescompris-iii.;r a snrrounding tubular body through which the material tobe heated is adapted to pass, the remaining! electrodes being embeddedin the body of material to be heated through which the currents pass,`the disposition and spacing apart of said electrodes producingsubstantially-uniform heating of the briquets, substantially asdescribed.

5. A polyphase alternating-current electric heating` furnace. forchemical reactions, comprising an outer tubular electrode through whichthe 4material to be heated is adapted to pass, said electrode .beingoonnected to the common return conductor of a polyphase circuit, and apluralit of,elec trodes within and spaced away rom said outer electrodeand connected to the remaining terminals of said circuit, thedisposition of said electrodes being such that the material to betreated disposed around and be'- tn'een them will besubstantially-uniforinly heated, substantially as described.

6. A polyphase alternating-current electric heating furnace for chemicalreactions, comprising an outer electrode forming a plurality of chambersthrough which the. material to he treated is ada ted to pass and eachcontaining an electrode spaced away from the walls of its chamber andadapted to be ernbedded in the material traversing its chamber,substantially as described.

7. A polyphase alternating-current electric heating furnace for chemicalreactions, comprising an outer electrode connected to the common returnconductor of a polyphase circuit and shaped to rovide a plurality ofchambers through Wliich the material to be treated is adapted to pass,and each containing anelectrode spaced away from the walls of itschamber and adapted to be embedded in the material traversing itschamber, said inner electrodes being connected to the remainingconductors of said polyphase circuit, substantially asdescribed.

MARK SHOELD.

